Weird noise when using denoise
I don't think this is a materials issue.

I think what's happening is this: you have a low number of samples (it looks like it's definitely below 64). You mentioned you are using a denoiser, which works fine on other renders. However, this scene doesn't have a lot of light, so the signal-to-noise ratio is low, and the denoiser is having a hard time, producing artifacts. The solution would be to increase the number of samples. Using at least 256 might be a good idea:



Another factor that might have increased the amount of noise is that there is little direct lighting - some places need at least 2 bounces for light to reach them. The solution would be to add some more light sources. For example, you could put an emitting plane right behind the window. This would allow light to reach more places.

If this doesn't work for you, please add more information to the question. It's not easy to guess the problem from a single image :) !